Dementia is caused due to damage to nerve cells in the brain. The damage affects the ability of the brain cells to communicate with one another. This affects the thinking, language, and behavior of a person. Depending on the area of the brain where the damage has occurred, dementia affects different people in different ways. The different types of dementia are grouped on the basis of which part of the brain is affected or whether it is progressive or not.
Non-progressive dementia is caused as a reaction to certain medication or vitamin deficiency. With appropriate treatment, a person may recover from this type of dementia. Progressive dementia gets worse over time.

Types of progressive dementia

• Alzheimer’s disease : This is the most common form of dementia in people older than 65 years. There are no known specific causes of Alzheimer’s; genetic factors are often responsible for the onset of this type of dementia.
• Vascular dementia : This type of dementia occurs when there is damage in the vessels that supply blood to the brain. The damage is caused by illnesses such as stroke that affect the blood vessels.
• Lewy body dementia : This is one of the most common forms of progressive dementia. Lewy bodies are found in the brain. These are abnormal clumps of protein that have been observed to be present in people with Parkinson’s disease, Alzheimer’s disease, and Lewy body dementia.
• Frontotemporal dementia : This is caused by the breakdown or degeneration of nerve cells present in the frontal and temporal lobes of the brain. These areas of the brain are usually associated with language, behavior, and personality.
• Mixed dementia : In some cases, a combination of vascular dementia, Lewy body dementia, and Alzheimer’s disease causes dementia. This is known as mixed dementia.

Symptoms
The symptoms of dementia differ based on the cause and the part of the brain affected. However, there are a few common symptoms and signs. These are usually cognitive changes or psychological changes. Cognitive symptoms include memory loss, difficulty in communicating, difficulty in finding words while speaking, difficulty in reasoning or problem-solving, difficulty in handling complex tasks, difficulty in planning and organizing, difficulty with motor functions and coordination, confusion, and disorientation. Psychological changes include depression, personality changes, anxiety, inappropriate behavior, agitation, paranoia, and hallucinations.

Risk factors
The probability of the occurrence of dementia increases with certain risk factors. Here are some of the known risk factors for dementia:

• Age : The risk of dementia increases with age. People who are older than 65 years have the highest risk of dementia.
• Genes : A person who has a family history of dementia is at high risk. However, there have been cases when a person ends up with dementia despite not having any family history. There are certain tests that have been developed to determine whether someone has the specific genetic mutations that result in dementia.
• Down syndrome : It has been observed that people who have Down’s syndrome may develop onset of dementia by middle age.
• Mild cognitive impairment : This occurs when there are difficulties with memory. However, there is no loss of daily function. Such people are at very high risk of dementia.
• Heavy alcohol consumption : Drinking high amounts of alcohol on a regular basis increases the risk of dementia.
• Cardiovascular risk factors : Ailments such as hypertension, high cholesterol, atherosclerosis, and obesity also increase the probability of dementia.